Like many corporate boards, the nine directors that lead Microsoft are seldom seen or heard when it comes to company matters.

But according to veteran Microsoft analyst Rick Sherlund, Microsoft’s board has been under intense pressure from activist shareholder ValueAct Holdings to improve shareholder value. And that may well have included a threatened proxy battle for a board seat if Microsoft did not replace its CEO.

“It’s not clear how big a role ValueAct played here, but I suspect they were a strong catalyst for change,” Sherlund said. “Threatening to go out and conduct a proxy contest is the equivalent to dragging (Steve) Ballmer as well as the board and Bill (Gates) through the mud for what’s happened to the company over the last 10 years.”

Jeffrey Ubben, ValueAct Capital’s chief executive, did not respond to a request for comment. And in an interview with The Seattle Times, Ballmer was clear that pressure from ValueAct played no role in his decision to retire.

“No. My retirement has nothing to do with that,” Ballmer said. “My retirement has everything to do with what I think is the right long-term timing for Microsoft.”

But Sherlund believes that ValueAct has been accumulating the sort of leverage it needs to effect change.

While the firm owns about 1 percent of the outstanding shares, Sherlund believes it has the support of a large number of shareholders who have watched Microsoft’s shares languish for more than a decade.

Shareholders certainly applauded the news of Ballmer’s departure. The stock climbed as high at $35.20, before closing at $34.75, a 7 percent jump.

In July, Reuters reported that members of Microsoft’s board met with ValueAct to discuss its demands for a board seat. Reuters also reported that high among ValueAct’s concerns was the lack of succession planning for Ballmer.

Microsoft director John Thompson told The Seattle Times in an interview that the board has been focused on succession.

“We’ve had a process under way for quite some time,” said Thompson, chief executive of Virtual Instruments and the former CEO of security software maker Symantec. “I’ve been on the board myself for about 18 months, and in every meeting we’ve talked about succession.”

One question that remains is whether Ballmer’s pending departure will be enough to quell ValueAct. Sherlund doesn’t think so.

“I don’t think they are in it to see the stock go over $35,” Sherlund said. “This is not finished. They want it over $40.”

Now Sherlund is looking toward Aug. 30. That’s the deadline by which shareholders must notify Microsoft of intentions to fight a proxy battle.

Sherlund thinks ValueAct will push for a commitment from Microsoft to massively buy back stock and increase its dividend in order to boost shareholder value by then in exchange for holding off on a proxy fight.

“ValueAct could say, ‘I don’t need to be on the board if Microsoft does that,’ ” Sherlund said.